Risk factors of deficit and non-deficit schizophrenia: Results from a cross-sectional study

Aim: It has been observed that deficit and non-deficit schizophrenia (SCZ-D and SCZ-ND) might be characterized by different risk factors. Therefore, the present study aimed to assess as to whether previously reported risk factors of schizophrenia are specifically associated with SCZ-D and SCZ-ND.

Method: This study was based on a cohort of 118 stable outpatients with schizophrenia. A diagnosis of SCZ-D was established using the Schedule for the Deficit Syndrome (SDS). Risk factors were recorded using structured interview, the Operational Criteria for Psychotic Illness (OPCRIT) checklist and the Traumatic Experience Checklist (TEC). The following risk factors were explored: male sex, a history of schizophrenia in first-degree relatives, seasonality of birth, birth weight <3000g, delivery by cesarean section, a history of childhood trauma (emotional abuse, emotional neglect, physical abuse and sexual abuse) as well as substance abuse (other than nicotine) and cigarette smoking at psychosis onset.

Results: Individuals with SCZ-D were more likely to be males as well as reported higher rates of birth weight <3000g and any categories of childhood trauma. In turn, substance abuse (other than nicotine) at psychosis onset was significantly more frequent in patients with SCZ-ND. Binary logistic regression, controlling for multiple comparisons, revealed similar findings, except for the association with any categories of childhood trauma that appeared to be not significant.

Conclusion: Our findings partially replicate differential patterns of risk factors for SCZ-D (male sex and birth weight <3000g) and SCZ-ND (substance abuse at psychosis onset), likely attributable to the effects of timing of exposure.